nunny Posted July 31, 2008 Share Posted July 31, 2008 Has anyone or does anyone know if its possible to run someting like http://www.mr-resistor.co.uk/item.aspx?&am...=429&I=3727 off a rechargable battery source, I have to try to find a solution for a stand alone colour changing system which needs to be as compact as possible, or if this isnt possible just a nice icy white colour may suffice, I think LED is the only way it may be possible The battery will need to last approximately 4-5 hours, Any suggestions would be great, Thanks in advance. Mike Link to comment Share on other sites More sharing options...
boatman Posted July 31, 2008 Share Posted July 31, 2008 Has anyone or does anyone know if its possible to run someting like http://www.mr-resistor.co.uk/item.aspx?&am...=429&I=3727 off a rechargable battery source, I have to try to find a solution for a stand alone colour changing system which needs to be as compact as possible, or if this isnt possible just a nice icy white colour may suffice, I think LED is the only way it may be possible The battery will need to last approximately 4-5 hours, Any suggestions would be great, Thanks in advance. Mike From the description on the website it should be possible to run those from a car battery. A fully-charged 80AH battery will supply 15A for about 5 hours and as each lamp is only 5W you should be able to run 30 for the time you require. Don't forget that a fully charged car battery is closer to 14V and you shouldn't discharge them to much below 9V, so it would be worth getting one lamp and trying it with a benchtop variable supply to see what range of voltage it can cope with. Link to comment Share on other sites More sharing options...
nunny Posted July 31, 2008 Author Share Posted July 31, 2008 What about just running one off a single battery, is there any compact batteries available??? Maybe similar to the ones found in twin head emergency luminaires?? http://www.budgetbatteries.co.uk/22028/ene...d-acid-battery/ Would this work and how long would it run Thanks Mike Link to comment Share on other sites More sharing options...
berry120 Posted July 31, 2008 Share Posted July 31, 2008 It would work and probably last about 1 1/2 hours if I've got my calculations right. Link to comment Share on other sites More sharing options...
nunny Posted July 31, 2008 Author Share Posted July 31, 2008 Would I be right in thinking off a 12v source a 5w fixture will be pulling 2.08a over 5 hr, I came to this by using the power triangle, by dividing 5w by 12v I got the current to be 0,41a the multiply this by 5????? Does this sound right?? Regards Mike Link to comment Share on other sites More sharing options...
boatman Posted July 31, 2008 Share Posted July 31, 2008 Would I be right in thinking off a 12v source a 5w fixture will be pulling 2.08a over 5 hr, I came to this by using the power triangle, by dividing 5w by 12v I got the current to be 0,41a the multiply this by 5????? Does this sound right?? Regards Mike Your numbers are correct but the units are wrong. It should be 2.08Ah (Ampere hours). The mistake is understandable as the Budget Batteries website also uses incorrect units. There doesn't seem to be an ideal battery for your purpose, but this battery would run one lamp for 25 hours or five lamps for five hours. Link to comment Share on other sites More sharing options...
adam2 Posted August 1, 2008 Share Posted August 1, 2008 The spec states that the lamp uses 5 watts at 12 volts DC.This may be easily obtained from a 12 volt rechargeable battery, sealed lead acid is probably most suitable.5 watts at 12 volts is a little less than 0.5 amp, therefore it would appear that to power one lamp for 5 hours, a 2.5 amp/hour battery is required. In practice a larger battery is required for two reasons, firstly the stated capacity is under ideal conditions and may not be reached in practice, and secondly the capacity of a battery is generally determined if discharged over 20 hours, if discharged over 5 hours as proposed, the capacity will be less.I would suggest a 12 volt, 7 amp/hour, sealed lead acid battery for a single lamp. These batteries are widely sold at prices from about £10 to £20.For mulitple lamps a larger battery will be needed, I suggest at least 5 amp/hours per lamp. Remember that these batteries can supply hundreds of amps if short circuited, which is a fire risk. To ensure safety, a fuse should be fitted as close as possible to one of the battery terminals, a vehicle type in line fuseholder with a 3 amp fuse is suitable. Link to comment Share on other sites More sharing options...
musht Posted August 1, 2008 Share Posted August 1, 2008 Starter/charger battery packs like: http://www.maplin.co.uk/Module.aspx?Module...e=1&DOY=1m8 quite a convenient way to have a portable power source, 17Ah SLA in handy housing. Link to comment Share on other sites More sharing options...
adam2 Posted August 1, 2008 Share Posted August 1, 2008 Starter/charger battery packs like: http://www.maplin.co.uk/Module.aspx?Module...e=1&DOY=1m8 quite a convenient way to have a portable power source, 17Ah SLA in handy housing. Very good value, I doubt that you could buy the battery and charger for that, remember though that the 17 A/H is under perfect conditions and if discharged over 20 hours. Link to comment Share on other sites More sharing options...
nunny Posted August 1, 2008 Author Share Posted August 1, 2008 Thanks for your help guys, I will try a 12v 7ah bench test next week. Mike Link to comment Share on other sites More sharing options...
musht Posted August 2, 2008 Share Posted August 2, 2008 If you use multiple batteries , charging regime becomes a potential problem, big charger and all batteries in parallel has its disadvantages. The booster packs have a standard SLA inside, 17Ah seems to be popular size for electic golf carts as well. Charger is a 12V 500mA wall wart usually, but charger per battery makes it simpler. Link to comment Share on other sites More sharing options...
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